According to Larry Cohen, during the St. Patrick's Day Parade scene, he was organizing the crew, only to see Andy Kaufman, dressed in his policeman's uniform, antagonizing and making faces at the crowd. Some of the crowd members then attempted to jump the barricades and beat Kaufman, and Cohen had to hold them back.
Larry Cohen did not have a permit to film the scene at the St. Patrick's Day parade, but he did it anyway.
Tony Lo Bianco accidentally broke actor William Roerick's rib performing CPR in the heart attack scene.
Composer Bernard Herrmann, Larry Cohen's first choice to score the film, died that night after seeing the film without music. The film is dedicated to Hermann in his honor.
When Larry Cohen asked composer Miklós Rózsa to score this picture, Rozsa replied, "God told me not to."